Be sure to not make your topic too broad. It should cover a specific town or area, not the entire world or a country, but does not have to be the particular town or area where you live. Please stay away from global issues.
As an example, runoff from a coal mine may be contaminating the groundwater of a nearby town. A solution to abating the contaminated groundwater could be to shut down the coal mine but at the cost of everyone losing their jobs. A benefit to this solution could be clean drinking water for the community. Notice that the topic is not all coal mines but rather this one very specific coal mine. Identify the location when presenting the introduction and explaining the problem.
There are a host of other costs and benefits associated with the solution to the above example. There are also many alternatives for solutions, none of which would make everyone happy. It is your job to find these costs and benefits for whatever solutions you choose. Do so through reading, watching, and summarizing your findings. You need research to support each cost and benefit. Then, analyze each solution’s costs and benefits to determine which is the best solution. Remember when considering costs and benefits, they go far beyond dollar values (e.g., loss or gain of jobs, land use, recreation, convenience, public health, habitat loss or gain, pollution).
Include a slide with the title of your presentation, then 1-2 introduction slides describing the environmental problem in detail. The main body of the presentation should describe the solutions and the costs/benefits of the proposed solution and give recommendations based on the cost/benefit analysis. Be sure to use APA style citations and include a reference slide.
A PowerPoint presentation is really just an outline (with topics, subtopics, and bulleted statements), so it only contains the main points (just like you make an outline when writing a research paper). If you have never used or, there are many tutorials on the internet that explain how to create a presentation. It is better to have a detailed, well-organized, well-written presentation than a lengthy one that rambles off of the topic.